CMAKE_<LANG>_FLAGS
Flags for all build types.
<LANG> flags used regardless of the value of CMAKE_BUILD_TYPE.
This is initialized for each language from environment variables:
- CMAKE_C_FLAGS:
Initialized by the CFLAGS environment variable.
- CMAKE_CXX_FLAGS:
Initialized by the CXXFLAGS environment variable.
- CMAKE_CUDA_FLAGS:
Initialized by the CUDAFLAGS environment variable.
- CMAKE_Fortran_FLAGS:
Initialized by the FFLAGS environment variable.